A steam turbine plant customarily comprises the steam turbine as such and a steam turbine peripheral equipment arrangement. The peripheral equipment arrangement in this case serves inter alia for feed and discharge of superheated steam to or from the steam turbine respectively. By means of the peripheral equipment arrangement on the inlet side the superheated steam is fed to the turbine at a high temperature and to a turbine casing at high pressure. For this purpose, the superheated steam is first fed to an inflow region of the turbine, which basically extends between a connection of a steam boiler to the turbine and the start of a blading in the casing or on the rotor of the turbine, as the case may be. In the steam turbine, the superheated steam, as working medium, is passed by the turbine blades, cooling and expanding, and in this way drives the rotor of the turbine, yielding its thermal and kinetic energy. The rotation can be used for driving a generator and for producing electric current there. The expanded and cooled working medium can recirculate in the form of cooled and expanded steam in the peripheral equipment arrangement on the outlet side, for example via a condenser.
In order to increase the efficiency of such a steam turbine plant, it is necessary inter alia to increase the pressure and the temperature of the working medium, that is the superheated steam. This results in a multiplicity of additional or increased stresses of the materials which are used in the components with high thermal loads, especially in the peripheral equipment arrangement of the turbine plant, the inflow region, casing region or rotor region of the turbine of the turbine plant. Therefore, at high operating temperatures, for example on account of chemical reactions of the material with the working medium inter alia, an increased oxidation rate occurs, which leads to scaling to an increased degree. This is undesirable and causes multifarious problems, inter alia with regard to the sealing performance of the respective component or components which are connected downstream.
For solving such problems, up to now the solution has been to use more superior materials for the piping components and/or collecting components, especially in the peripheral equipment arrangement of the turbine plant, in the inflow region and/or in the casing region or rotor region of the turbine of the turbine plant. High temperatures of the components, however, as a rule also result in a lowering of the permissible mechanical stress, which in turn limits the use of still more superior materials not only in the components themselves, but also in their structural anchoring.
More superior materials are not only cost-intensive, but also labor-intensive with regard to their processing and their use. Principles of cooling for components of a steam turbine plant are basically known, however result in losses in efficiency of the entire plant.
Therefore, the solution has been to attach insulations, in part, especially in the case of components which are subjected to high thermal loads. Up to now, these were applied for example with pipes, boilers or headers of the peripheral equipment arrangement, within the scope of a spraying method in which a coating powder is thermally sprayed on.
In addition to this, it is known to attach heat insulating fabric on a hot side of a component of the peripheral equipment arrangement, which hot side faces a superheated steam space. Such heat insulating materials as a rule can be applied in layers with high thickness and in principle would be well suited. However, within the limits of higher operating temperatures and higher operating pressures, in the meantime the flow characteristics of steam flows in and/or on a component, for example already on account of the flow velocity, are aggressive in such a way that the aforementioned heat insulating materials prove to be insufficiently strong and after a short time can already be destroyed and/or detached, for example as a result of erosion, other abrasion, and/or as a result of oxidation. This effect is increased more by thermo-shock stresses, which make the materials brittle or in any case create stresses. Detached heat insulating materials then get into the flow of the working medium and can lead to a further increasing of erosion damage both in the peripheral equipment arrangement and in the turbine of the turbine plant.
A lining with simultaneously high heat insulating characteristics and high abrasion resistances would be desirable. Up to now, increasing heat insulation by increasing a thickness of a heat insulating layer in the way which is explained above, leads to a reduction of the mechanical resistance. Increasing the mechanical resistance by reducing the thickness of a heat insulating layer, on the other hand leads to a lower thermal resistance, since the heat insulation also reduces with reducing thickness.
The invention starts at this point, the object of which is to disclose a component of a steam turbine plant for exposure to admission of superheated steam, a steam turbine plant, and also an application and a production method, according to which in equal measure a thermal and mechanical resistance of the component, even at increased temperature and pressure parameters of a superheated steam, especially at temperatures of above 600° C. and/or pressures of above 250 bar, is advantageously improved.